1. Technical Field
The present invention relates to a brushless motor, particularly to a brushless motor designed to have reduced vibration energy and reduced torque loss.
2. Description of the Related Art
A conventional structure of a brushless motor (hereinafter, referred to as a “motor”) allows vibration energy, generated by a reaction of a field magnet of an armature, to be conducted through an armature retaining member such as a motor case in which the armature is retained. Consequently, the vibration energy is conducted through the armature retaining member and to the entire motor. Particularly, in a Power Electric-Assist System (hereinafter, referred to as “EPS”) in which steering of a vehicle operated by a driver is assisted by a motor, the vibration energy generated within the motor will be conducted to a handle of the vehicle, and thus, affecting the operability of the vehicle. In order to counter such vibration energy affecting the operability of the vehicle, a motor structure in which an annular spacer is circumferentially provided between the armature and the armature retaining member has been used.
However, since the spacer is circumferentially provided, a large area where the spacer and the armature retaining member make contact with each other will be generated. Therefore, the vibration energy of the armature will be conducted to the armature retaining member through a large area. This causes large vibration energy to be conducted from the spacer to the armature retaining member, thereby causing large vibration energy to be conducted within the motor. Therefore, there is an increased demand for a motor which generates smaller vibration energy than what is conventionally offered.